| 摘要 |
A vacuum package bag, e.g., for ground coffee, comprises opposite walls having a gas exhaust valve running along one end of the bag and formed by two parallel transverse weld lines defining a channel at least 5 mm wide. At least one gap is formed in the inner weld line at the upstream end of the channel to define a passageway between the bag and the channel, and an opening is formed at the downstream end of the channel for communication with the surrounding atmosphere. The weld lines have at least one pair of inwardly projecting protuberances defining narrowed sections of the channel. A spot weld is provided along the longitudinal axis and substantially along the continuation of the upstream oblique sides of each pair of protuberances and preferably slightly downstream thereof. Supplementary webs define converging passages between the downstream-most passageway and the upstream-most pair of protuberances.
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